1. Field of the Invention
Apparatuses and methods consistent with the present general inventive concept relate to an image forming apparatus, and more particularly, to an image forming apparatus capable of controlling a developer exhausting amount according to an average printing density and an image forming method thereof.
2. Description of the Related Art
In general, an image forming apparatus forms image data stored in a host apparatus on a printing medium according to a printing signal. The image forming apparatus is provided with an image receptor in which an electrostatic latent image is formed, a developer transfer body that selectively spreads developer on the photoreceptor, and a transfer unit that transfers the developer developed on the photoreceptor to the printing medium to print a desired image on the printing medium. The image forming apparatus can be embodied by a printer, a photocopier, a scanner, and a multifunctional printer including these apparatuses.
The developing cartridge is detachably provided in the above-described image forming apparatus, and is provided as consumables that can be replaced if developer stored inside of the cartridge is exhausted.
As illustrated in FIG. 1, a conventional developing cartridge 10 comprises an electrifying part 12 which electrifies an image receptor 11 to a predetermined electric potential, the photoreceptor 11 which is electrified to a predetermined electric potential through the electrifying part 12 so that an electrostatic latent image is formed on its surface by an exposure of a light scanning unit (not illustrated), a developer transferring body 13 which is in contact with the photoreceptor 11 and spreads developer on the electrostatic latent image of the surface of the photoreceptor 11, a supplying part 15 which supplies the developer to the developer transferring body 13, a developer regulating member 14 which regulates an amount of the developer supplied to the developer transferring body 13, and a developer storing part 16 which stores developer.
Hereinafter, an operation of the conventional developing cartridge will be described. In a printing operation, a printing signal is received and the developer transferring body 13 supplied with developer from the supplying part 15 rotates, and maintains a developer layer having a uniform thickness by the developer regulating member 14. Also, the developer transferring body (or the developing roller) 13 rotates in a direction opposite to a rotation direction of the photoreceptor 11 and is in contact with the photoreceptor 11, and the developer supplied to the surface of the developer transferring body 13 is transferred to the electrostatic latent image of the photoreceptor 11 by a potential difference of the photoreceptor 11 to form a visible image on the photoreceptor 11. Also, the developer on the photoreceptor 11 is transferred to the printing medium by a transfer roller 20, and forms an image on a printing medium.
However, the conventional developing cartridge 10 repeatedly performs the above-described process regardless of an amount of the image data applied from a host apparatus (not illustrated). That is, even though the amount of the image data to which a printing signal has been applied is small, the above-described process is performed. Accordingly, if the amount of the image data is extremely small, the developer discharged from the developer storing part 16 by the supplying part 15 cannot be transmitted to the photoreceptor 11 and may rotatably remain in a peripheral area A proximate to the developer transferring body 13 and the supplying part 15.
Here, where the image data of the printing signal is extremely small, the discharged developer continues rotating in a peripheral area A proximate to the developer transfer part 13 and the supplying part 15 and comes to be under stress by contact with a frame or contact among particles of the developer. Also, if the developer is under stress, an internal additive and an external additive forming the developer may be separated from each other, or its shape may be deformed. Furthermore, if an image is formed on the printing medium by the deformed developer, a developing property and a fusing property deteriorate to thereby worsen print quality.